Phase II trial of cyclophosphamide, vincristine, and dexamethasone in the treatment of androgen-independent prostate carcinoma

BACKGROUND. In this Phase II study, the authors assessed the toxicity and antitumor activity of a combination of oral cyclophosphamide, oral low-dose dexamethasone, and intravenous vincristine (CVD) in patients with metastatic androgen-independent prostate carcinoma (Al-PCa). METHODS. Patients with histologic proof of adenocarcinoma of the prostate progressing despite adequate hormonal therapy and adequate organ function were treated with oral cyclophosphamide, 250 mg/daily (Days 1-14); intravenous vincristine, 1 mg daily (Days 1, 8, 15); and oral dexamethasone, 0.75 mg twice a day (Days 1-14) in 28-day cycles. Study endpoints were toxicity, rate of prostate specific antigen (PSA) decline > 50%, and/or measurable disease response. RESULTS. Fifty-two (95%) of 55 registered patients were evaluable. The majority (65%) of patients had received prior chemotherapy. The median number of treatment cycles given was two (range, one-seven cycles). Twenty-nine percent of the patients were found to have a > 50% decline in PSA level compared with baseline levels, and 25% of the patients with bidimensionally measurable soft-tissue or visceral disease were found to have a partial response. The median progression-free survival duration was 10 weeks, and the median overall survival duration was 10.6 months. There were no thromboembolic events, and hematologic and nonhematologic toxicity was minimal. CONCLUSIONS. CVD was found to be an active and well-tolerated regimen for AI-PCa. The low toxicity profile makes CVD a useful treatment option for patients with significant comorbidities and high risk for treatment- related toxicity, especially thromboembolic events and myelotoxicity. Cancer 2003;97:561-7. (C) 2003 American Cancer Society.